Q. What is vision? Why is vision important for life on earth?
Vision is the ability of some living beings to distinguish, to perceive and to interpret luminous stimuli.
Vision is important on earth mostly in the terrestrial and in the superficial aquatic habitats because our planet is intensely exposed to sunlight and thus light and colors become distinguishing factors of objects present in the environment even at distance. This distinction provided new protection mechanisms against external dangers, new survival strategies for the organisms, new ways to find food and to communicate with other individuals, new types of courting and reproduction behaviors, and so on. That is, it created new possibilities of interaction with the surrounds and increased capacity to explore new ecological niches.